Dragon Ball Z: Fusion Reborn

In the Afterlife, a teenage "oni" guarding a spirit cleansing machine turns the volume of his walkman up so loud that he fails to change the evil essence tank when necessary. Due to the overload of evil essence, the machine explodes and the "oni" is transformed into a huge-childlike monster with power over the laws regarding the worlds of the living and the dead. As a result, Multiverse are thrown into chaos: in the living world, several deceased are brought back to life, while in the other world, beings who were allowed to keep their bodies turn into spirits, and vice versa.